US5309447A - Space compression technique for pseudo-exhaustive self-testing of digital electronic circuits - Google Patents

Space compression technique for pseudo-exhaustive self-testing of digital electronic circuits Download PDF

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US5309447A
US5309447A US07/709,740 US70974091A US5309447A US 5309447 A US5309447 A US 5309447A US 70974091 A US70974091 A US 70974091A US 5309447 A US5309447 A US 5309447A
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bit
response signal
pattern
circuits
sub
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US07/709,740
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Marsha R. Moskowitz
Eleanor Wu
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Nokia Bell Labs
AT&T Corp
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AT&T Bell Laboratories Inc
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Assigned to AMERICAN TELEPHONE AND TELEGRAPH COMPANY, A CORPORATION OF NY reassignment AMERICAN TELEPHONE AND TELEGRAPH COMPANY, A CORPORATION OF NY ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: MOSKOWITZ, MARSHA R., WU, ELEANOR
Priority to KR1019920008839A priority patent/KR960011530B1/ko
Priority to EP19920304900 priority patent/EP0517444A3/en
Priority to JP4161847A priority patent/JP2607000B2/ja
Priority to TW081104274A priority patent/TW208763B/zh
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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F11/00—Error detection; Error correction; Monitoring
    • G06F11/22—Detection or location of defective computer hardware by testing during standby operation or during idle time, e.g. start-up testing
    • G06F11/26—Functional testing
    • G06F11/27—Built-in tests
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F11/00—Error detection; Error correction; Monitoring
    • G06F11/28—Error detection; Error correction; Monitoring by checking the correct order of processing

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  • This invention relates to a method and apparatus for compacting (compressing) response signals produced by a digital electronic circuit under test.
  • pseudo-exhaustive testing of an electronic circuit is carried out by first partitioning the circuit into individual sub-circuits, hereinafter referred to as "cones,” each having only one output and no more than a predetermined number of inputs.
  • a test generator is added to the circuit under test for generating a set of vertical canonical vectors at its output.
  • a separate subset of the canonical vectors is then assigned to the inputs of each cone such that the vectors in each subset are independent of each other to assure exhaustive testing of the cone.
  • each cone Upon receipt of a test vector at its inputs, each cone generates a response signal bit.
  • the response signal bits from the cones are compacted (compressed) to yield a reduced length stream of bits indicative of the response of the cones, which is determinative of whether the circuit contains any faults.
  • MISR Multiple Input Shift Registers
  • a typical MISR comprises a plurality of MISR cells daisy-chained together to form a circle, with each cell containing an exclusive OR (XOR) gate having a first input supplied with the response bit from an observation point, such as the output of a cone, and a second input supplied with the output of an upstream MISR cell.
  • XOR exclusive OR
  • Each MISR cell also comprises a flip-flop whose input is supplied with the output of the XOR gate of the cell and whose output is supplied to an input of the XOR gate of a downstream MISR cell.
  • the pattern of bits (referred to as a "signature") stored by the MISR will be indicative of the operation of the circuit.
  • compaction of multiple streams of response signals each stream generated by a separate set of sub-circuits within an electronic digital circuit under test, is accomplished by first recognizing whether each corresponding set of sub-circuits produces a response signal having a particular pattern associated therewith. For each set of sub-circuits, a pattern bit is generated indicative of whether the response signal has the particular pattern. By producing a pattern bit indicative of whether the response signal of the corresponding set of sub-circuits has a particular pattern, the bits in such response signal are effectively "space-compressed" into a single bit.
  • Each pattern bit associated with a corresponding set of sub-circuits is then time-compacted by a separate one of a set of time-compaction cells, each having its output linked to the input of another in daisy-chain fashion.
  • Each time-compaction cell serves to exclusively OR the pattern bit with a compacted bit output by an upstream time-compaction cell.
  • the resultant bit produced following the exclusive OR operation is then stored, typically in a flip-flop in the cell, for subsequent input to a downstream time-compaction cell for exclusive OR'ing with the pattern bit input thereto.
  • the bits stored by the time-compaction cells represent a history of the patterns of the response signals during testing, which greatly aids in fault detection.
  • FIG. 1 is a model of a conventional electronic circuit under test
  • FIG. 2 is a schematic view of a preferred embodiment of a space compressor in accordance with the present invention.
  • FIG. 1 is a model of a conventional electronic circuit 10 typically comprised of AND, OR, NOR, NAND and NOT gates (not shown).
  • the circuit is partitioned into sub-circuits or cones 12 1 , 12 2 . . . 12 n , only four of which are shown in the illustrated embodiment.
  • the purpose in subdividing the circuit 10 into the cones 12 1 , 12 2 . . . 12 n is to facilitate exhaustive testing thereof by applying a set of canonical test vectors, which are independent of each other, to each cone.
  • a determination can be made as to whether the circuit is operating properly.
  • the testing of a large circuit 10 is facilitated by analyzing whether the stream of response signals associated with each of a set of cones 12 i has a particular bit pattern and then generating a pattern bit indicative of whether the pattern is present. By compacting the pattern bits over time, the occurrence or sequence of the particular pattern can be determined, which provides a good indication of whether the circuit is operating properly.
  • each bit in the response signal stream can only be at one of two states (a "0" or a "1"), then only 2 3 or eight patterns of the response signals are possible as shown in FIG. 1.
  • the exact sequence of the possible response signal stream patterns is dependent on both the pattern of canonical vectors applied to inputs of the cones 12 1 , 12 2 , 12 3 and the faults (defects), if any, therein.
  • a particular one of the eight separate patterns for example, the pattern [0 1 1]
  • the pattern [0 1 1] will appear only at certain times when a given set of canonical test vectors is applied to the inputs of the cones 12 1 , 12 2 and 12 3 .
  • a determination can be made as to whether the circuit 10 is operating properly.
  • FIG. 2 shows a combination of pattern recognition and compaction units 14, in accordance with the invention, each recognizing the pattern of the response signal for each set of cones 12 i , for generating a pattern bit indicative of the presence of such a pattern, and for compacting the pattern bit with other such pattern bits over time so that the units collectively yield a compacted bit stream indicative of the sequence of patterns in the response signal streams.
  • a logic gate 16 typically and AND or NAND gate having as many inputs as bits in the response signal stream.
  • the inputs to the logic gate 16 are selectively inverted, by way of one or more inverters 18, so that the logic gate only "recognizes” a particular pattern. In other words, the gate 16 will output a bit at a logic "1" level only when a particular pattern of bits is present at its inputs.
  • the gate 16 In order for the gate 16 to recognize the pattern [0 1 1], the first input of the gate is inverted by the inverter 18, as seen in FIG. 2, the remaining inputs not being inverted. Other patterns of interest would require others of the inputs to the gate 16 to be inverted accordingly. Note that if the particular pattern of interest is [1 1 1], no inversion of the inputs of the gate 16 is required for the gate to recognize the pattern.
  • the output bit of the logic gate 16, hereinafter referred to as the pattern bit, is input to a Multiple Input Shift Register (MISR) cell 20 associated with the logic gate for compacting the pattern bit produced thereby with another compacted bit produced by another MISR cell.
  • MISR Multiple Input Shift Register
  • each MISR cell 20 associated with a group of cones 12 i is daisy chained with each of the other MISR cells in a loop.
  • Each MISR cell 20 comprises an exclusive OR (XOR) gate 22 having a first input, supplied with the pattern bit output by its associated gate 16, and a second input supplied with a compacted bit from an upstream MISR cell associated with another set of cones 12 i .
  • the XOR gate 22 has its output input to a flip-flop 24 whose output forms the output of the cell 20 which is input to a downstream MISR cell 20.
  • each group of cones 12 i Associated with each group of cones 12 i is a separate pattern recognition and compaction unit 14, as indicated by the presence in FIG. 2 of two such units, the second shown by dashed lines.
  • the second input to the XOR gate of each MISR cell 20 of each pattern recognition and compaction apparatus 14 is supplied with the output of the MISR cell associated with an upstream recognition and compaction apparatus.
  • the output of the flip-flop 24, which forms the output of the MISR cell 20 is input to the second input of the XOR gate 22 of a downstream cell.
  • the output of the last MISR cell 20 in the chain is typically exclusively OR'd with the output of another cell in the chain via an XOR gate 26 before being fed back to the first cell.
  • each corresponding cone set will produce a response signal input to the corresponding gate 16 of its corresponding pattern recognition and compaction unit 14.
  • the gate 16 will output a pattern bit whose state is indicative of whether the response signal has the particular pattern, for input to the XOR gate 22 of the associated MISR cell 20.
  • the bit i.e., the "compacted" bit
  • the bit stored by the flip-flop 24 of the upstream MISR cell 20 will typically be a "0" so that the bit produced by the gate 16 will be passed directly to the flip-flop 24 of the MISR cell associated with that gate.
  • each test vector applied subsequently to a set of cones 12 i the process is repeated, except that the bit stored by each flip-flop 24 of each MISR cell 20 is now determined by both the state of the compacted bit stored by the upstream MISR cell as well as the state of the current pattern bit.
  • the bits stored by the MISR cells 20 in the chain reflect the history of the patterns of the signals generated by the sets of cones 12 i .
  • the pattern recognition and compaction unit 14 of the present invention affords a distinct advantage over other compaction schemes.
  • a conventional MISR (not shown) which is comprised of a plurality of cells, each identical to the MISR cell 20, the pattern recognition and compaction unit 14 imposes a smaller circuit overhead.
  • a conventional MISR a separate cell (identical to each MISR cell 20) is required for each observation point (i.e., for each cone 12 i ). Since each cell of a conventional MISR requires at least 20 grids (gates) for implementation, at least 60 grids would be required for a group of three cells.
  • the logic gate 16 of the pattern recognition and compaction unit 14 of the invention can generally be implemented with four grids. With the addition of the inverter 18 (two grids) as well as the MISR cell 20 (twenty grids), a total of twenty-six grids are consumed, a significant savings as compared to a conventional MISR.
  • the pattern recognition and compaction apparatus 14 also facilitates very high fault coverage, that is, very high detection of faults in the circuit 10 of FIG. 1.
  • very high fault coverage that is, very high detection of faults in the circuit 10 of FIG. 1.
  • the cones 12 1 , 12 2 and 12 3 are supplied with a set of canonical test vectors, only eight separate response signal patterns are possible.
  • a determination can be made whether the circuit has any faults.
  • fault coverage of between 98.5% and 99.5% has been found achievable using the pattern recognition and compaction units 14 of the invention.
  • the foregoing describes an apparatus 14 which advantageously serves both to recognize the presence of a particular response signal stream pattern produced by a circuit 10 under test and to compact information related to the sequence of the occurrence of such a pattern.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • Computer Hardware Design (AREA)
  • Quality & Reliability (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Tests Of Electronic Circuits (AREA)
US07/709,740 1991-06-03 1991-06-03 Space compression technique for pseudo-exhaustive self-testing of digital electronic circuits Expired - Lifetime US5309447A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
US07/709,740 US5309447A (en) 1991-06-03 1991-06-03 Space compression technique for pseudo-exhaustive self-testing of digital electronic circuits
KR1019920008839A KR960011530B1 (ko) 1991-06-03 1992-05-25 응답 신호를 압축시키는 방법 및 장치
EP19920304900 EP0517444A3 (en) 1991-06-03 1992-05-29 Space compression technique for pseudo-exhaustive self-testing of digital electronic circuits
JP4161847A JP2607000B2 (ja) 1991-06-03 1992-05-29 電子回路の故障検出装置及び故障検出方法
TW081104274A TW208763B (fr) 1991-06-03 1992-06-01

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US07/709,740 US5309447A (en) 1991-06-03 1991-06-03 Space compression technique for pseudo-exhaustive self-testing of digital electronic circuits

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EP (1) EP0517444A3 (fr)
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TW (1) TW208763B (fr)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5771242A (en) * 1995-06-07 1998-06-23 International Business Machines Corporation Memory array built-in self-test circuit having a programmable pattern generator for allowing unique read/write operations to adjacent memory cells, and method therefor
US5796745A (en) * 1996-07-19 1998-08-18 International Business Machines Corporation Memory array built-in self test circuit for testing multi-port memory arrays
US5918003A (en) * 1995-06-07 1999-06-29 International Business Machines Corporation Enhanced built-in self-test circuit and method
US6665828B1 (en) * 2000-09-19 2003-12-16 International Business Machines Corporation Globally distributed scan blocks
US20060069951A1 (en) * 2002-05-15 2006-03-30 Ralf Arnold System for testing digital components
US20060111873A1 (en) * 2004-03-31 2006-05-25 Yu Huang Compactor independent direct diagnosis of test hardware
US20070100586A1 (en) * 2004-03-31 2007-05-03 Wu-Tung Cheng Direct fault diagnostics using per-pattern compactor signatures
US20070283202A1 (en) * 2004-03-31 2007-12-06 Wu-Tung Cheng Compactor independent fault diagnosis
US20130024830A1 (en) * 2011-06-08 2013-01-24 Huaxing Tang Fault Diagnosis Based On Design Partitioning

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US4864570A (en) * 1987-06-29 1989-09-05 International Business Machines Corporation Processing pulse control circuit for use in device performing signature analysis of digital circuits
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US4996689A (en) * 1989-02-01 1991-02-26 Vlsi Technology, Inc. Method of generating tests for a combinational logic circuit
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US5189675A (en) * 1988-06-22 1993-02-23 Kabushiki Kaisha Toshiba Self-diagnostic circuit for logic circuit block
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Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5771242A (en) * 1995-06-07 1998-06-23 International Business Machines Corporation Memory array built-in self-test circuit having a programmable pattern generator for allowing unique read/write operations to adjacent memory cells, and method therefor
US5790564A (en) * 1995-06-07 1998-08-04 International Business Machines Corporation Memory array built-in self-test circuit having a programmable pattern generator for allowing unique read/write operations to adjacent memory cells, and method therefor
US5918003A (en) * 1995-06-07 1999-06-29 International Business Machines Corporation Enhanced built-in self-test circuit and method
US5796745A (en) * 1996-07-19 1998-08-18 International Business Machines Corporation Memory array built-in self test circuit for testing multi-port memory arrays
US6665828B1 (en) * 2000-09-19 2003-12-16 International Business Machines Corporation Globally distributed scan blocks
US20060069951A1 (en) * 2002-05-15 2006-03-30 Ralf Arnold System for testing digital components
US7386776B2 (en) * 2002-05-15 2008-06-10 Infineon Technologies Ag System for testing digital components
US20070283202A1 (en) * 2004-03-31 2007-12-06 Wu-Tung Cheng Compactor independent fault diagnosis
US20070100586A1 (en) * 2004-03-31 2007-05-03 Wu-Tung Cheng Direct fault diagnostics using per-pattern compactor signatures
US20060111873A1 (en) * 2004-03-31 2006-05-25 Yu Huang Compactor independent direct diagnosis of test hardware
US7729884B2 (en) 2004-03-31 2010-06-01 Yu Huang Compactor independent direct diagnosis of test hardware
US20100306606A1 (en) * 2004-03-31 2010-12-02 Yu Huang Compactor independent direct diagnosis of test hardware
US8280688B2 (en) 2004-03-31 2012-10-02 Mentor Graphics Corporation Compactor independent direct diagnosis of test hardware
US8280687B2 (en) 2004-03-31 2012-10-02 Mentor Graphics Corporation Direct fault diagnostics using per-pattern compactor signatures
US8301414B2 (en) * 2004-03-31 2012-10-30 Mentor Graphics Corporation Compactor independent fault diagnosis
US20130024830A1 (en) * 2011-06-08 2013-01-24 Huaxing Tang Fault Diagnosis Based On Design Partitioning
US8707232B2 (en) * 2011-06-08 2014-04-22 Mentor Graphics Corporation Fault diagnosis based on design partitioning

Also Published As

Publication number Publication date
EP0517444A3 (en) 1993-08-04
JP2607000B2 (ja) 1997-05-07
EP0517444A2 (fr) 1992-12-09
KR960011530B1 (ko) 1996-08-23
JPH06249917A (ja) 1994-09-09
TW208763B (fr) 1993-07-01

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